An optical filter is used to select a spectral band or a spectral component of incoming light. A high pass filter, for example, selects light at wavelengths longer than an edge wavelength of the filter. Conversely a low pass filter selects light at wavelengths shorter than an edge wavelength. A bandpass filter is a distinct type of filter, which selects light at wavelengths proximate to a center wavelength of the filter within a bandwidth of the filter. A tunable bandpass filter is an optical filter, the center wavelength of which may be adjusted or tuned.
A spectrometer measures an optical spectrum of incoming light. A scanning-type spectrometer may use one or more tunable bandpass filters to select different spectral components of the incoming light. A scanning-type spectrometer operates by scanning the center wavelength of the tunable bandpass filter, so as to obtain the optical spectrum. Alternatively, a polychromator-type spectrometer uses a wavelength-dispersing element optically coupled to a detector array for parallel detection of the optical spectrum. However, conventional optical filters and spectrometers are typically large and bulky, making it a challenge to use them in portable devices and applications.
In view of the foregoing, it may be understood that there may be significant problems and shortcomings associated with current solutions and technologies for optical filters and spectrometers.